Various pieces of equipment are operated by hydraulic or pneumatic pressure delivered to the equipment via a valve. The present invention relates to a piezoelectric based valve which is constructed to provide a tight seal against an exhaust opening of the valve so that the maximum pressure of a pressurized fluid is delivered to the equipment, thereby maximizing the efficiency thereof.
Valves including piezoelectric elements are well known in the patented prior art as evidenced by the Kowanz U.S. Pat. No. 5,779,218 and Frisch et al. U.S. Pat. No. 5,343,894. In the known devices, an end of the piezoelectric element moves between open and closed positions. Since most piezo devices are thin, elongated elements, the closing force at a remote end of the devices is limited, whereby leakage of fluid pressure occurs.
The present invention was developed in order to overcome this and other drawbacks of prior piezo-based valves by providing a unique mounting arrangement for the piezoelectric element which significantly increases the sealing force applied by the movable end of the element.
Accordingly, it is a primary object of the invention to provide a valve including a housing containing a chamber, a recess at one end, and a pressurized fluid input, a working fluid outlet, and an exhaust outlet at the other end. An elongated piezoelectric element is arranged in the chamber and operable between inactive and active conditions to close the pressurized fluid inlet and exhaust outlet, respectively, with a first end portion thereof. The piezoelectric element is mounted in the chamber via two supports. A first support is connected with the other end of the element and is arranged in the housing recess for rotational and longitudinal movement therein as the piezoelectric element shifts between active and inactive conditions. A second support is connected with the piezoelectric element toward the first end portion thereof and is rotatably connected with the housing. When the element is activated by the application of an electrical signal, it bends. The second support rotates relative to the housing but prevents vertical displacement of that portion of the element. Thus, the bending force at the first end portion of the element is significantly greater to seal the exhaust outlet and deliver all of the pressurized fluid to the working outlet and then to a piece of equipment connected therewith. When the electrical signal is not applied, including in the event of a power failure, the element returns to the planar condition to close the pressurized fluid inlet.
According to a further object of the invention, sealing members are connected with opposite surfaces of the first end portion of the piezoelectric element to assist with closing the pressurized fluid inlet and exhaust outlet. The sealing members and the first and second supports are preferably formed of synthetic plastic material.